Figure 3.

Olfactory function. (a) Electrophysiological recordings from the antennal basiconic sensillum 3 (ab3), which houses two neurons (ab3A and ab3B) that express Or22a/b and Or85b, respectively. The neurons can be distinguished both by ‘spike’ (action potential) amplitude and their responses to different odours (diluted to 0.001% v/v in the paraffin oil solvent and presented during 1 s). Adapted from [22] (copyright © Cold Spring Harbor Laboratory Press). (b) Combinatorial coding of odours by Ors: the first large-scale profiling of responses of many Ors to a chemically diverse panel of stimuli. Here, Ors were transgenically expressed in the ‘empty’ Or22a/b neuron (lacking the endogenous receptors) to provide a consistent cellular background for comparison of receptor function. Data are replotted from [61]; the scale is shown on the right. Negative responses reflect odours that decrease the basal spiking frequency of neurons. Some receptors for which no strong agonists were identified (e.g. Or47b) were later found to respond to pheromones [67,68].